Symptoms related to alterations of the autonomic nervous system are frequent in patients with multiple sclerosis (MS). Bladder or bowel dysfunction or impairment of sexual performance is highly distressing for most MS patients, whereas the clinical relevance of other autonomic symptoms is less clear. Cardiovascular autonomic alterations might relate to clinical signs such as orthostatic intolerance; a relationship with fatigue is uncertain. However, the frequency of abnormal findings in tests for the cardiovascular autonomic system varies due to the lack of standardized test performance or differentially used cut-off values. The incidence of additional symptoms such as pupillomotor or sweating alterations and especially their relationship to overall autonomic nervous system abnormalities is not well known. Although their impact on daily life is low, they can at least serve as diagnostic tools. Beside these clinical aspects, alterations of the autonomic nervous system have also been reported to alter immunological cascades in experimental conditions. However, corresponding results have not been confirmed in clinical trials yet.